
/// UI 状态类
sealed class UiState {

   const UiState();

   factory UiState.loading() = Loading;
   factory UiState.success() = Success;
   factory UiState.error() = Error;
}

final class Loading extends UiState {

  const Loading();

}


final class Success extends UiState {

  const Success();

}

final class Error extends UiState {

  const Error();

}
